1. Field of the Invention
The present invention relates to a window for insertion into walls of various thicknesses and including connection means which cannot be easily detected from the outside, providing good resistance to burglary.
2. Description of the Related Art
Extruded windows are known, for example, in U.S. Pat. No. 4,407,100. The frames are constructed from extruded profile sections being cut at the ends at an angle of 45.degree., before being assembled by gluing, to form closed frames of the desired size. By assembling the window frames at the corners, it is possible to produce window frames of any size. However, the cutting and assembly add to the number of time consuming steps needed in production, and the assembly must be made carefully in order to avoid weakness in the frame. The design of the profiles of these known windows comprises various hollow spaces and cannot be manufactured by methods other than extrusion molding from plastic and aluminum. The windows made from extruded profiles, however, may be made with a good resistance against burglary, owing to the hidden design of the connection means.
French Patent No. 2,154,931 discloses a window including burglary resistant means. The toothed connection means comprises hooks gripping into openings in the frame member of the first frame. On each of the sides of the window a few hooks and corresponding openings are used for holding together the two frames after insertion. A disadvantage of this known window type is that the placement of the hooks is easily detectable from the outside and can be overcome by a burglar, whereby the window is not effectively secured against burglary. Furthermore, there is only one position in which the hooks are locked, whereby the window is intolerant to variations in the thickness of the wall in which it is to be inserted.